R.I.P. NASA Satellite Kepler, 2009-2018

NASA artist's concept of Kepler doing its job

NASA artist’s concept of Kepler doing its job

NASA Satellite Kepler, the exo-planet-discovering super hero, was taken off life support on October 30, 2018.1 The 2,750 pound satellite will be left in solar orbit, trailing the Earth by some 94 million miles.

Kepler was the child of William Borucki, the retired Kepler principal investigator, who first proposed the satellite in 1992. It was named for the 17th century German astronomer Johannes Kepler who discovered the laws of planetary motion and contributed to the development of optics,2 Kepler was launched March 6, 2009 and began acquiring data April 8, 2009.

Kepler launch, March 6, 2009

Kepler launch, March 6, 2009

Analysis in January 2010 of that data revealed the first five exo-planets, Kepler-4b, -5b, -6b, -7b and -8b, planets that are “hot Jupiters” — gas-giant infernos — orbiting their parent stars in a matter of days, with surface temperatures above 2,000 degrees Fahrenheit. By mid-March, Kepler had doubled the number of known exo-planets, and kept going from there. The list of Kepler’s discoveries is astonishing: the first rocky exo-planet, the first exo-planet orbiting a double star, the first habitable zone exo-planet; the list goes on and on.

In May 2013, Kepler developed a mechanical problem – the failure of the second of three reaction wheels that kept Kepler focused on a single patch of sky. As a result, Kepler was repurposed. Using the pressure of sunlight to stabilize the spacecraft, the mission continued, with the satellite’s field of view changing every three months. The re-configured Kepler kept making discoveries, ranging from the death of a planet to an incipient supernova. And included an amazing 8-planet exo-solar system.

In the original field of view, a small patch of stars about 20 full moons wide in the constellation Cygnus, the final tally from Kepler’s first four years of data included 4,034 candidate planets, with 2,335 of those confirmed. As many as 12 of those exo-planets are rocky planets, in orbits in the “habitable zone,” and could support life as we know it.

Some extremely impressive statistics

Some extremely impressive statistics

An altogether amazing job. WC’s offers his congratulations and condolences to the NASA team, to Ball Aerospace & Technologies, who built Kepler, and everyone else on the Kepler team.

Kepler taught us there are more planets than stars. That’s a decent epitaph. R.I.P., Kepler, 2009-2018.3


  1. NASA calls it “retirement.” That’s a euphemism. It’s shut down. It’s dead. 
  2. It’s hard to imagine a better name. Exo-planet detection depends upon Kepler’s laws of planetary motion and advanced optics. 
  3. Yes, this is WC’s first obituary for a satellite. And it is richly deserved.